1. Field of the Invention
The invention relates to a fuel cell and a method of assembling the same.
2. Description of the Related Art
A generally known fuel cell is constructed by laminating a plurality of single cells each having a membrane electrode assembly (hereinafter referred to as the MEA) interposed between two separators. The MEA is composed of an electrolytic membrane and gas diffusion electrodes. Platinum as catalytic electrodes is applied to both surfaces of the electrolytic membrane, which is interposed between the gas diffusion electrodes. The catalytic electrode and the gas diffusion electrode formed on one surface of the MEA constitute an anode, and the catalytic electrode and the gas diffusion electrode formed on the other surface of the MEA constitute a cathode. A fuel gas passage for causing hydrogen gas as fuel gas to spread into a single cell is formed in a separator facing the anode. An oxidative gas passage for causing air as oxidative gas to spread into the single cell is formed in a separator facing the cathode.
If the width of the dispersion of output voltage among single cells constituting a fuel cell is increased, the overall performance of the fuel cell may deteriorate. Thus, as is disclosed in Japanese Patent Laid-Open Application No. 2000-208161, there is an art wherein output voltages of single cells are individually monitored during operational control of a fuel cell, wherein a standard deviation of the output voltages is calculated, and wherein electric current density, reactive gas flow rate, or reactive gas pressure is controlled on the basis of the standard deviation with a view to maintaining high performance of the fuel cell as a whole.
Even if electric current density, reactive gas flow rate, or reactive gas pressure is thus controlled on the basis of a standard deviation of output voltages of single cells, such control alone has its limitations in suppressing the influence of dispersion of output voltage among the single cells.